Jimmie Johnson’s series-high sixth victory of the season Sunday was tempered by word that a plane carrying two pilots and eight passengers crashed into a mountain Sunday afternoon en route to the Subway 500 NASCAR Nextel Cup race.

Ten people were confirmed dead, including four relatives of Hendrick Motorsports CEO Rick Hendrick: His son Ricky Hendrick, his brother John Hendrick, and John’s twin daughters, Jennifer and Kimberly. John, 53, was the president of Hendrick Motorsports. Ricky owned a Busch series NASCAR team and ran Performance Honda of Pineville, N.C., a motorcycle dealership.

Also killed in the crash were five Hendrick Motorsports employees: general manager Jeff Turner; Randy Dorton, the chief of the company’s engine program; Scott Latham, a pilot for Tony Stewart, and company pilots Dick Tracey and Liz Morrison. The 10th victim was Joe Jackson, an executive with DuPont, which sponsored Jeff Gordon’s Hendrick Motorsports car.

NASCAR learned of the plane’s disappearance during the race and withheld the information from the Hendrick drivers — Johnson, Gordon, Terry Labonte and Brian Vickers — until afterward, spokesman Jim Hunter said. All the Hendrick drivers were summoned to the NASCAR hauler immediately after the race, and Johnson was excused from victory lane.

The plane took off from Concord, N.C., and crashed into Bull Mountain, about 10 miles west of the Martinsville Blue Ridge Regional Airport, shortly after 12:30 p.m., Federal Aviation Administration officials said.

Emergency teams in Patrick County responded, but the plane appeared to have crashed in a remote area, said Keith Holloway, a National Transportation Safety Board spokesman.

It remains unclear what caused the crash of the Beech 200 King Air plane, he said. In the past five years, 12 similar models have crashed around the world, killing their passengers, according to NTSB records.

The plane was among a fleet owned by the North Carolina motorsports company. Hendrick had four teams competing in Sunday’s race.